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Overview
Comment:Fix a problem causing an infinite loop or other malfunction in some UPDATE statements with an OR term in the WHERE clause. Ticket [47b2581aa9bfecec]
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SHA3-256: feb2c2b6f66b0f45490beb1642d99cdb89fa220e299a8c118929df557c814189
User & Date: dan 2018-01-16 13:37:43
Original Comment: Fix a problem causing an infinite loop or other malfunction in some UPDATE statements with an OR term in the WHERE clause.
Context
2018-01-16
17:33
Change a cat in zipfile.c from (z_const Bytef*) to just (Bytef*). This allows the module to build with older versions of zlib. check-in: ac9af91d user: dan tags: trunk
13:37
Fix a problem causing an infinite loop or other malfunction in some UPDATE statements with an OR term in the WHERE clause. Ticket [47b2581aa9bfecec] check-in: feb2c2b6 user: dan tags: trunk
02:38
Disable the ".archive" command tests in shell8.test if the CLI is compiled without ZLIB support. check-in: ce8bfe6c user: drh tags: trunk
Changes
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Changes to src/where.c.

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    }
  }
  WHERETRACE(0xffff,("*** Optimizer Finished ***\n"));
  pWInfo->pParse->nQueryLoop += pWInfo->nRowOut;

  /* If the caller is an UPDATE or DELETE statement that is requesting
  ** to use a one-pass algorithm, determine if this is appropriate.
















  */
  assert( (wctrlFlags & WHERE_ONEPASS_DESIRED)==0 || pWInfo->nLevel==1 );
  if( (wctrlFlags & WHERE_ONEPASS_DESIRED)!=0 ){
    int wsFlags = pWInfo->a[0].pWLoop->wsFlags;
    int bOnerow = (wsFlags & WHERE_ONEROW)!=0;
    if( bOnerow
     || ((wctrlFlags & WHERE_ONEPASS_MULTIROW)!=0
           && 0==(wsFlags & WHERE_VIRTUALTABLE))

    ){
      pWInfo->eOnePass = bOnerow ? ONEPASS_SINGLE : ONEPASS_MULTI;
      if( HasRowid(pTabList->a[0].pTab) && (wsFlags & WHERE_IDX_ONLY) ){
        if( wctrlFlags & WHERE_ONEPASS_MULTIROW ){
          bFordelete = OPFLAG_FORDELETE;
        }
        pWInfo->a[0].pWLoop->wsFlags = (wsFlags & ~WHERE_IDX_ONLY);
      }







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    }
  }
  WHERETRACE(0xffff,("*** Optimizer Finished ***\n"));
  pWInfo->pParse->nQueryLoop += pWInfo->nRowOut;

  /* If the caller is an UPDATE or DELETE statement that is requesting
  ** to use a one-pass algorithm, determine if this is appropriate.
  **
  ** A one-pass approach can be used if the caller has requested one
  ** and either (a) the scan visits at most one row or (b) each
  ** of the following are true:
  **
  **   * the caller has indicated that a one-pass approach can be used
  **     with multiple rows (by setting WHERE_ONEPASS_MULTIROW), and
  **   * the table is not a virtual table, and
  **   * either the scan does not use the OR optimization or the caller
  **     is a DELETE operation (WHERE_DUPLICATES_OK is only specified
  **     for DELETE).
  **
  ** The last qualification is because an UPDATE statement uses
  ** WhereInfo.aiCurOnePass[1] to determine whether or not it really can
  ** use a one-pass approach, and this is not set accurately for scans
  ** that use the OR optimization.
  */
  assert( (wctrlFlags & WHERE_ONEPASS_DESIRED)==0 || pWInfo->nLevel==1 );
  if( (wctrlFlags & WHERE_ONEPASS_DESIRED)!=0 ){
    int wsFlags = pWInfo->a[0].pWLoop->wsFlags;
    int bOnerow = (wsFlags & WHERE_ONEROW)!=0;
    if( bOnerow || (
        0!=(wctrlFlags & WHERE_ONEPASS_MULTIROW)
     && 0==(wsFlags & WHERE_VIRTUALTABLE)
     && (0==(wsFlags & WHERE_MULTI_OR) || (wctrlFlags & WHERE_DUPLICATES_OK))
    )){
      pWInfo->eOnePass = bOnerow ? ONEPASS_SINGLE : ONEPASS_MULTI;
      if( HasRowid(pTabList->a[0].pTab) && (wsFlags & WHERE_IDX_ONLY) ){
        if( wctrlFlags & WHERE_ONEPASS_MULTIROW ){
          bFordelete = OPFLAG_FORDELETE;
        }
        pWInfo->a[0].pWLoop->wsFlags = (wsFlags & ~WHERE_IDX_ONLY);
      }

Changes to test/update2.test.

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do_test 5.2 {
  catch { array unset A }
  db eval { EXPLAIN UPDATE x1 SET c=c+1 WHERE b='a' } { incr A($opcode) }
  set A(NotExists)
} {1}

















finish_test







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do_test 5.2 {
  catch { array unset A }
  db eval { EXPLAIN UPDATE x1 SET c=c+1 WHERE b='a' } { incr A($opcode) }
  set A(NotExists)
} {1}

#-------------------------------------------------------------------------
do_execsql_test 6.0 {
  CREATE TABLE d1(a,b);
  CREATE INDEX d1b ON d1(a);
  CREATE INDEX d1c ON d1(b);
  INSERT INTO d1 VALUES(1,2);
}

do_execsql_test 6.1 {
  UPDATE d1 SET a = a+2 WHERE a>0 OR b>0;
}

do_execsql_test 6.2 {
  SELECT * FROM d1;
} {3 2}

finish_test